Normally the first generation of hybrid is supplied for farm rearing, precise and labor saving sex discrimination is needed. The new strain "Hansaengjam" is sex-limited ( :larval markings, :no-markings) strain which was bred from both sex-limited strain Japanese

This study was conducted to confirm the possible use of female Yangwonjam as a host for synnemata production of Isaria tenuipes in eight local areas in Korea. Silkworm pupation rate, infection rate and synnemata characteristics of I. tenuipes were examined. Normal silkworms had a higher pupation rate than silkworms inoculated with I. tenuipes. The pupae survival percentage of normal silkworm in cocoons was 92.5~97.6%, whereas it ranged from 91.1~95.6% in silkworms sprayed with I. tenuipes. Female Yangwonjam showed the highest survival percentage at 97.6% among the silkworm varieties tested. I. tenuipes infection rate of larvae of 5th instar newly-exuviated silkworms was 89.2~90.7% in the spring rearing season and 98.2~99.3% in the autumn rearing season. Synnemata production of I. tenuipes was excellent in female Yangwonjam with an incidence rate of 98.0% followed by male Yangwonjam (94.1%) and Baegokjam (93.3%) in the spring rearing season. Synnemata living weight ranged from 1.44~0.94 g in the spring rearing season. The female Yangwonjam had the heaviest synnemata weight (1.44 g) in the spring rearing season. The synnemata of I. tenuipes produced on pupae were white or milky-white in color, and were similar in shape and color to wild synnemata collected in Korea.

Yeonnokjam is a newly bred high yield special silkworm strain for spring rearing, bred from Japanese originated green cocoon spinning strain Jam 315 and Chinese originated white cocoon spinning strain Jam 316. This strain showed high hatching ratio of 96% and high healthiness of 96.7% of pupatin ratio. And its spins heavier cocoon with somewhat shorter fiber length but thicker fineness. The merits of these strains are short larval period and labor saving, and its breeding goals are producing polish green silk and use for education.

A new silkworm variety SooOkJamfor spring rearing season is F 1 hybrid between Jam157, a japanese race bred from introduction breeding and Jam158, a chinese race from introduction breeding. In the local adaptability test performed at 8 local areas in spring of 2011, the hatchability rate of SooOkJam was recorded 2% higher than the authorized silkworm variety, DaePoongJam. The larval period was recorded 12 hour shorter than DaePoongJam. The pupation percentage was recorded 0.8% higher than DaePoongJam. Single cocoon weight (2.40 g), Cocoon yield (22.6 kg) and best cocoon rate (95.5%) was similar to DaePoongJam. The concentration of DNJ was measured 4.12 mg in SooOkJam, lower than DaePoongJam (4.45 mg). Test of the artificial diet of SooOkJam showed excellent adaptability of the artificial diet for larval period from 1st to 3rd, similar to KumOkJam. In the Paecilomyces tenuipes production ability test, the pupal weight of SooOkJam was 1.61 g/individual, similar to DaePoongJam (1.65 g/individual).